1. Field of the Art
This invention relates to a saponin-containing galenical extract and a product isolated therefrom and more particularly to an absorption adjuvant composition for aiding adsorption of drugs to be absorbed or administered through the alimentary system. This invention is based on a finding relating to the pharmacological characteristics of this galenical extract capable of aiding, particularly promoting, absorption of a pharmacologically active substance administered through or into the alimentary system, e.g., orally or by insertion into the rectum.
2. Prior Art
Because of the difficulty in isolation by purification of saponin and its complicated structure, it has not been very long ago, only about ten and some years ago, when marked progress in research on saponin appeared.
As typical characteristics of saponins, they foam when shaken with water, act as powerful hemolytics by dissolving red blood corpuscles, are poisonous toward fish, and can form complexes with cholesterol (a steroid). As pharmaceuticals, they have been found to have pharmacological activities such as expectorant, antibechic, antiinflammatory, central nervous system blocking, antifatigue, antiulcer, cholesterol metabolism promoting, lipid metabolism promoting and nucleic acid or protein synthesis promoting activities. In addition, it has also recently been found that they have anti-infective and antitumor activities. Saponin-containing galenicals with relatively higher saponin contents listed in the Japanese Pharmacopoeia may include Senega, Polygala Root, Platycodon Root, Glycyrrhiza, Achyranthes Root, Bupleurum Root, Panax Rhizome, Ginseng, Ophiopogon Tuber, Akebia Stem, etc.
Saponins can be classified according to the chemical structures of the sapogenin or aglycone moieties thereof into steroid saponins and triterpenoid saponins. Triterpenoid saponins containing hederagenin as aglycone are obtained from various plants such as Akebia guinata Decne. (Chem, Pharm, Bull. 24, 1021 (1976)), Caulophyllum robustum Maxim. (C.A. 85, 106644h (1976), Fatsia japonica. Decne. (Phytochemistry 15, 781 (1976)), Sapindus mukurossi Gaertn. (C.A. 73, 77544, 110062m, 110071p (1970) and C.A. 74, 13384f (1971)), Lecaniodiscus cupanioides Planch. ex Benth (Phytochemistry 20, 1939 (1981)). But no systematic pharmacological research has been developed so far. Bupleurum root saponin, which is one of triterpenoid saponins, has very potent hemolytic and local excitory actions, exhibiting sedative, antalgic, hypothermal, antipyretic actions and anti-inflammatory effect, and it is also effective for digestive ulcer. As for a saponin from the peels of Sapindus mukurossi Gaertn., which is another triterpenoid saponin, it has not previously been used for medical purpose, but investigations about its anti-inflammatory action have been made due to similarlity in chemical structure. There is a report that it exhibited inhibitory effect in carragheenin edema and adjuvant arthritis of rats.
In spite of discovery of various pharmacological activities of saponin as mentioned above, systematic pharmacological research has just begun, and it can be expected in the future that a novel pharmacological effect not known in pharmaceuticals of prior art will be discovered.
On the other hand, in the administration of an antibacterial preparation, there is known the concept of minimal effective concentration in blood. At a level lower than such concentration, a drug is not effective even if it may exist persistently for a long time in a body. For this reason, the utilization percentage by absorption of a drug to be absorbed through the alimentary system is very important, and there have heretofore been investigations on methods for maintaining effective concentrations in blood with smaller amounts of drugs by enhancement of the absorption efficiency of drugs from the standpoint of either preparation or administration technique.
However, it would be greatly beneficial, if the absorption utilization percentage could be enhanced by administration of a conventional drug for oral administration according to a conventional oral administration method.